Diet, exercise, sleep, genetics and the environment are factors generally recognized as strongly influencing health. Sunlight as a detrimental environmental factor causing skin cancer and other conditions is often discussed. The beneficial effects of sunlight have had much less attention.
For many individuals moderate increases in ultraviolet sunlight exposure as in outdoor work, careful sunbathing or lamp exposure can provide systemic benefits. The benefits include: decreased blood pressure, decreased resting heart rate, increased cardiac output, reduced blood cholesterol, increased liver glycogen stores, reduced blood sugar, increased muscular strength and endurance, increased resistance to infections, increased oxygen carrying capacity of the blood, increased adrenaline in tissues, increased stress tolerance, and increased hormones, Kime, 42.
The purpose of this invention is to provide methods and apparatus to increase the exposure of the skin when the exposure might be deficient such as during dark winter days and decrease the exposure when the exposure might be excessive such as during bright spring and summer days. The proper exposure of skin to solar radiation especially in a changing environment is important to promote health and reduce the risk of disease. An indoor deficiency in ultraviolet B (280 nm to 315 nm) is common Excessive dietary vitamin D intake with associated problems results from attempts to compensate for the ultraviolet B exposure deficiency. Methods to increase the indoor ultraviolet B (UV-B) exposure, to avoid a deficiency in exposure and possible vitamin D deficiency while minimizing the risk of overexposure are included.
Irregular exposure such as excessive weekend and vacation sunlight exposure for persons working indoors during the week is a common problem. Irregular exposure is prevalent in developed countries and is a factor in the increasing incidence of the often fatal melanoma of the skin. Another purpose of the invention is to provide apparatus and methods to obtain a better balance in the day to day ultraviolet exposure of the skin.
Not enough sunlight and vitamin D deficiency can result in poor health and susceptibility to illness. Rickets in children, easy-to-break bones in the elderly, a possible increased susceptibility to some types of cancer, Ainsley, 9, and heart disease, Kime, 42, are typical conditions associated with insufficient UV-B sunlight exposure. The annual health care cost for fractures in the elderly is approximately 10 billion dollars in the U.S. alone, Avioli, 13. Scragg, 70, found coronary heart disease mortality may be associated with vitamin D deficiency (avoidable by sufficient UV-B exposure of the skin).
Sunlight exposure is beneficial for moderating hypertension, high blood sugar and many other conditions, Kime, 42. However, too much sunlight exposure increases the risk of skin cancer and DNA mutations. There is a need to adjust the skin exposure to avoid both insufficient exposure and excessive exposure. The best exposure for an individual varies with skin characteristics. The ratio between too much and too little exposure may be relatively small such as less than a factor of roughly three for face and arm exposure or relatively large such as a factor of 25 for whole body exposure.
Sunlight exposure is related to the important calcium balance. Modern populations have a low calcium diet presumed to result in increased osteoporosis, hypertension and colon cancer, Heaney, 38. The exposure to sunlight can increase the absorption of calcium in the intestine partially counteracting the effects of low amounts of calcium in the diet. Also, sunlight exposure is associated with increased bone mineralization, Kime, 42. Calcium, important in the functioning of cells, interacts strongly with vitamin D (and thus UV-B sunlight exposure), phosphorus, and magnesium. Too much calcium can result in urinary stones and interference with absorption of other essential minerals, Williams, 84. In infancy, excess vitamin D intake may result in hypercalcemia, Oppe, 61.
Vitamin D fortification of many foods is used in the U.S. for protection from rickets and other diseases for those with insufficient vitamin D generated in the skin by ultraviolet B exposure. However, the average person has an intake several times the recommended daily amount. As discussed by Kummerow, 45, and Fraser, 27, an increased mortality and incidence of vascular disease and other conditions may be resulting from high dietary intake of vitamin D. Linden, 49, found myocardial infarction patients had high intakes of vitamin D. Knox, 43, found increased ischemic heart disease mortality for those with high vitamin D intake and also for those with low calcium intake.
Fraser, 27, recommends obtaining the vitamin D from careful sun exposure rather than the diet. Along with obtaining proper exposure of the skin, the diet must be modified to avoid the excess dietary vitamin D intake to obtain the corresponding health benefits. Increased intake of fruits and vegetables tends to reduce intake of other foods with high vitamin D content due to fortification. Although vitamin D is needed primarily in the dark season in northern areas, the extensive fortification is present continuously during the year and is present in the foods for both northern and southern areas.
Historically, problems with insufficient exposure became common in the 1800's in higher latitude cities. With the start of the industrial revolution people moved from farms to cities. The narrow streets and smoke filled sky obscured the sunlight as shown by a photograph of a typical neighborhood, Goldsmith, 32. The incidence of rickets in children increased and this was later found to be due to insufficient ultraviolet B solar radiation exposure. The solar radiation UV-B was obscured both indoors and outdoors. Factory work rather than farm work greatly reduced sun exposure.
Those still involved in farm work tend to have good health for many conditions. The Gambia, is a West African, primarily agricultural country with both men and women cultivating the crops. There is significant outdoor exposure and a mainly vegetarian diet. This country has one of the lowest age standardized cancer incidences in the world. The incidence is more than five times lower than the incidence in the United States. In the U.S., a study in 1941 demonstrated states with a higher percentages of farmers had a trend for lower cancer mortality rates. States with a higher solar radiation index had an even stronger trend for lower cancer mortality, Apperly, 12.
The rickets problem was generally solved by the addition of vitamin D to milk and other foods. However, too much vitamin D may produce toxic effects such as hypercalcemia, Oppe, 61. Excessive vitamin D can be lethal and it is used as a rodenticide, Fraser, 27. Too much vitamin D can cause damage to the arteries. A typical desirable ratio of recommended maximum to recommended minimum dietary intake of vitamin D for infants is a factor of 2.5. Vitamin D generated in the skin by sunlight exposure has the advantage of only small amounts of vitamin D being released. The maximum accumulated amount of sunlight generated vitamin D in the skin is limited reducing the risk of toxic effects. In addition, the deleterious cholesterol in the skin and arterial plaque is reduced by sunlight exposure, Kime, 42. Cholesterol in the skin is converted to vitamin D and other compounds by exposure to UV-B radiation.
The narrow streets and smoke filled sky of the 1800's generally are no longer present However, the common economic low-melting-temperature window glass blocks most of the ultraviolet B radiation. If one were to photograph the insides of homes and businesses with an ultraviolet B camera, most would be dark to dim just as were the homes and streets of the 1800's. Bare fluorescent lamps without diffuser covers brighten the inside some. Open windows and doors in the spring and fall can brighten the inside of homes in the UV-B just as the mood and spirit brightens in sunny weather. However, now, many homes and workplaces switch from heating to air conditioning with little or no opening of windows in the spring and fall. This leaves an indoor environment with incandescent lighting essentially continually dark in the ultraviolet B spectral region. Hospitals with windows that do not open and fluorescent lighting with prismatic plastic diffusers also are essentially continuously dark in the UV-B.
Those of the elderly who are inside all the time and who do not obtain vitamin D from the diet or supplements can become deficient in vitamin D and develop weak easy-to-break bones. Even in bright countries such as Kuwait, rickets occurs since children spend much of their time inside, Lubani, 51. Dark skinned persons migrating to higher latitudes can encounter vitamin D deficiency problems. Recently, rickets from vitamin D deficiency was reported by Brunvand, 17, for Pakistani children in Oslo, Norway. One approach would be to drink more vitamin D fortified milk to compensate for the lack of vitamin D generated by UV-B irradiation of the skin.
Another approach could be to increase the UV-B radiation indoors by using UV-B transmitting windows or appropriate fluorescent lamps, an object of this invention.
For those who spend significant time outdoors, overexposure can be a problem in the spring and summer on bright days. During this period bare tube fluorescent lamps, Maxwell, 56, open windows, or open doors can aggravate the overexposure problem during long exposure periods indoors. A method of this invention is to move ultraviolet B blocking diffusers over bare fluorescent tubes in the bright season to avoid a possible exacerbation of the overexposure problem.
In cold climates, many persons are deficient in ultraviolet and visible solar radiation exposure of the skin in the winter due to blocking of ultraviolet solar radiation by window glass. Also the clothing worn outdoors in the winter covers much of the skin greatly reducing the exposure. The short length of the day at high latitudes restricts the time available for sunlight exposure. In addition, the low sun angle at midday in the winter at high latitudes reduces the ambient solar irradiation due to the long path length through the atmosphere. These factors make it desirable for some persons to increase the exposure of skin during the cold dark season. Leach, 46, found office workers in Bristol England receive less than an average of 0.7 mJ/sq. cm. per day of biologically effective radiation, a very low value, in the dark season from November through February, FIG. 1.
In hot climates the skin of many persons is excessively exposed to solar radiation. The long length of the summer day increases the time when solar radiation overexposure can occur. The high sun angle at midday in the summer increases the ambient solar irradiation due to the small amount of scattering and absorption in the short nearly vertical path length through the atmosphere. These factors make it desirable for some persons to decrease the exposure of the skin during the hot bright season.
The solar radiation in different spectral regions, UV-B, 280 to 315 nanometers, UV-A, 315 to 400 nanometers, visible light 400 to 700 nanometers and infrared radiation affect various health conditions. There are several suitable window materials such as ultraviolet transmitting glass or plastic with spectral transmission characteristics described by Driscoll, 23, and Sliney, 72. The increased cost of ultraviolet transmitting materials can be partially offset by using a small window orientated toward the sun for transmitting the solar radiation to a room frequently occupied such as a kitchen or living room.
The ultraviolet light rays, UV-B with a wavelength of 280 to 315 nanometers, are beneficial in the production of vitamin D in the skin. However, chronic exposure of untanned skin to ultraviolet solar radiation, especially UV-B, can be associated with DNA damage and an increased risk of skin cancer. Thus, care is needed to obtain adequate exposure in dark seasons and avoid excessive exposure in bright seasons. By reducing the bright season exposure more than the increase in the dark season exposure an increase in the risk of squamous cell skin cancer can be avoided, Lytle 53. By not chronically overexposing untanned skin an associated increase in the risk of melanoma skin cancer and other diseases can be avoided.
Vitamin D deficiency can be a problem for those confined indoors in nursing or other homes with insufficient ultraviolet exposure and a deficiency in dietary vitamin D. In some areas, especially far from the equator, there may not be sufficient sunlight for vitamin D generation in winter months. In addition to latitude, weather affects sunlight availability.
Dietary or tablet supplements are commonly used to avoid vitamin D deficiency. However, there may be problems associated with the use of dietary and tablet supplement vitamin D rather than solar radiation generated vitamin D. Large amounts of dietary or tablet supplement vitamin D can be ingested, however, vitamin D generated in the skin tends to self limit Accumulated cholecalciferol blocks further synthesis of vitamin D in the skin, Heaney, 38. Fraser, 27, states: “Evidence from domestic animals suggests that persistent feeding of dietary vitamin D may be associated with the development of chronic vascular disease. For this reason alone it is prudent to advise that vitamin D should be obtained from the environment by careful exposure of the skin to solar ultraviolet light rather than from the artificial source of dietary supplements.”
Latitudinal Variations in Incidence and Mortality
In addition to rickets and other disorders being associated with vitamin D deficiency, Garland, 29, postulates the increased breast cancer for more northerly, lower-solar-radiation areas in the United States may result from reduced solar radiation generated vitamin D. Colon cancer also is possibly associated with vitamin D deficiency by Garland, 30. Ovarian cancer also tends to have lower mortality rates for US women living in areas with more sunlight, Lefkowitz and Garland, 47. For prostate cancer, Studzinski, 77, discusses the studies indicating an increased mortality rate with reduced ultraviolet exposure, increased risk associated with higher serum levels of vitamin D binding protein and decreased risk associated with higher levels of serum 1,25 vitamin D3.
Multiple Sclerosis also has lower incidences in more southerly areas, Mason, 55. Many MS patients were found to be vitamin D deficient by Nieves, 59. Since heat intolerance is associated with MS and many are homebound without sunlight exposure, the deficiency was associated with being a result of the disease rather than a possible cause. However the latitudinal variation being similar to breast and colon cancer indicates vitamin D deficiency, solar radiation or climate induced processes might be considered as a partial cause, risk factor or aggravating factor for increased incidences of the disease. Waksman, 81, recommends influences such as climate, general levels of infection and neuroendocrine processes be investigated. Light induced neuroendocrine effects may be relevant
Equatorial regions tend to have low cancer incidences. The hot desert regions near 30 degrees latitude and the colder darker areas beyond 30 degrees latitude tend to have higher incidences for many types of cancer. For the equatorial regions the climate tends to be more uniform throughout the year with the length of days and nights balanced. The warm equatorial temperatures enable more skin to be exposed and the exposure is relatively uniform throughout the year. Also the diet tends to have more fruit and vegetables with low fat intake. The yearly solar radiation tends to be higher in the desert regions rather than at the equator. The fat intake tends to be higher for the developed countries at higher latitudes.
The many high population density areas near the equator tend to result in migration out of the area. The low rate of inward migration leaves a population with skin type well adapted for the local solar radiation environment over a very large number of generations. In lower population density areas at higher latitudes many dark skin persons are living in areas with low solar radiation exposure and many with light skin are living in hot bright climates. Increased migration has resulted in many living in stressful environments. The methods of this invention are directed toward increasing the exposure for those with skin better adapted for brighter environments and decreasing the exposure for those with skin better adapted for a darker environment
For skin and some other cancers the average incidence decreases with increasing latitude above 30 degrees north. These registries are primarily light skin registries. The higher incidences are in many cases for many persons with light skin living in brighter areas than their ancestors in northern Europe. For squamous cell and basal cell skin cancer the decrease is usually attributed to the lower total solar radiation dose at the higher latitudes. For melanoma of the skin the high incidences are often attributed to chronic exposure of untanned skin. An example is an indoor worker spending a lot of time in the sunlight on weekends and vacations resulting in many sunburns.
Seasonal Mortality Variations
If insufficient sunlight exposure and associated low vitamin D in the winter is associated with increased risk of diseases such as breast and colon cancer, an increase in morality in the winter is a possible consequence. For those diseases with increased mortality at higher latitudes with colder darker environments in the winter it might be expected to find an increased mortality in the winter months.
Since respiratory diseases are much more common in the low-temperature low-humidity winter season, increased incidences of other diseases are often considered to be a result of decreased resistance due to the respiratory conditions. The winter increase in respiratory diseases is large as shown in FIG. 2.
The mortality values for many other disease categories also are increased in the winter season, but not as much as for respiratory diseases, as illustrated by FIG. 2. The mortality for breast and colon cancer are slightly increased in the winter as shown in FIG. 3.
The seasonal variation of total mortality in Alaska is significantly different than the other states as illustrated by a comparison of FIGS. 2 and 4. In two years shown, 1989 and 1990 there is a narrow winter peak and a wide summer peak as shown in FIG. 4. In earlier years such as 1970 the summer peak is present in the vital statistics mortality tables for Alaska A possible cause for part of the summer mortality peak, other than ultraviolet exposure, is the reduced melatonin associated with the short summer nights in Alaska Decreased melatonin resulting from light at night, Blask, 16, has been postulated to be associated with increased disease incidence such as increased breast cancer.
The detrimental effects of short summer nights may be reduced by using room darkening curtains and low temperatures in the bedroom to make it possible to obtain adequate sleep in the summer, not only in Alaska, but in other states as well. Additional factors may be of importance in maintaining a sufficient melatonin concentration and duration. Increased disease incidence from living near electrical power lines or equipment with associated high electric and magnetic fields is believed to possibly be due to suppression of the nocturnal melatonin concentration as measured in animals, Kato, 41.
Mortality and Incidence Differences for Males and Females
In many western countries many females have increased sunlight exposure due to not working in an office or factory. Also, clothing styles in many countries tend to have more skin exposed for females than for males such as exposed lower legs for females. For many disease categories such as malignancies, females have lower mortality rates as would be expected if the average exposure is less than the optimum for best health. In some countries, such as Peru and Israel, males have lower malignancy incidence rates than females, WHO, 86, indicating the average exposure may be greater than optimum for females and possibly also for males.
In countries with a clothing style for females with most of the skin covered, the malignancy incidence rates for females is greater than for males such as in some registries in India, Parkin, 62. This indicates a possible underexposure for females. Techniques for obtaining additional private exposure (in conformance with religious beliefs) may offer health advantages for females.
Circulatory Disease Mortality, Countries with and without Extensive Vitamin D Fortification
In the U.S. many foods are fortified with vitamin D. In the U.K., France, Belgium, and the Netherlands fortification is used mostly for infants with small amounts for adults. The Netherlands specifically prohibit vitamin D fortification for items other than margarine and infant formulas according to the Tracor-Jitco report, reference FDA, 24. As shown by the mortality trends in FIG. 5, the Netherlands has a low all causes death rate and low circulatory system death rate. Since Fraser has associated dietary vitamin D with vascular disease, the circulatory disease mortality would be expected to be higher in the U.S. than the other countries not having vitamin D fortification for adult high intake dietary items such as bread, breakfast cereal, and milk.
Since there are many differences between the U.S. and the other countries other than vitamin D intake, the mortality difference may be due to other factors. For example, the lower circulatory disease mortality rate in France may be partially due to the regular consumption of moderate amounts of wine. However, since data for animals, Kummerow 45, demonstrates the adverse effects of excessive vitamin D, it is reasonable to consider vitamin D as a possible cause for part of the mortality differences.
FIG. 5 shows the generally higher age standardized incidence of circulatory disease in the U.S. compared with the countries without extensive adult dietary vitamin D fortification. Only for the U.K. for the last three periods is the circulatory death rate higher than the U.S. rate. Factors other than the vitamin D fortification may be responsible for the differences but the data indicate a significant fraction of the circulatory disease mortality possibly may be associated with vitamin D fortification.
In the U.K., the dietary intake of vitamin D was estimated to be 116 to 133 IU/day according to the FDA report, 25, by the Fed of Am Societies for Experimental Biology.
In 1967 Dale and Lowenberg, 20, estimated the intake for 150 U.S. subjects to be 547 IU/day. In his 1979 publication, Kummerow, 45, estimated the per capita U.S. intake to be about six times the RDA of 400 IU or about 2435 IU/day a very high value. However this value is based on the 10,000 lbs. of vitamin produced in the U.S. Of this 10,000 lbs. only 4000 lbs. was sold in 1969 (Tracor-Jitco report, FDA, 24) so the per capita intake is about 1000 IU/day or somewhat less considering losses in the amount sold prior to intake.
Exposure for Vitamin D Generation
The amount of skin exposure needed for vitamin D generation is not great. According to Mary Ellen Siegel, 72, the exposure time required for solar radiation induced vitamin D generation outdoors is only about 15 minutes of exposure of any area every two or three days. About 18 IU/sq. cm. per 3 hour period is generated in skin exposed to sunlight according to Loomis, 50. Thus, for 200 sq. cm. of skin exposed for 0.3 hours, 360 IU of vitamin D, or less due to limiting, would be expected. An ultraviolet transmitting window in a dwelling can provide sufficient exposure at a lower irradiance indoors for a longer exposure period. In a review article Anderson, 11, stated:
“The amount of skin biosynthesis per day is affected by many factors, such as latitude, sun (UV) exposure, dress, season of year, and skin melanin pigmentation. Webb, 82, estimated that only 15 to 20 minutes of exposure of arms and face at midday (c. 2 pm) will yield sufficient skin production of vitamin D sufficient to meet daily needs of adults living in Boston, Mass., USA i.e., 5 micrograms (or 200 IU). In the elderly, however, almost twice as much time is required to yield the same amount of vitamin D production by the skin.” These times are only for favorable seasons since Webb, 82, stated in his title: “Exposure to winter sunlight in Boston and Edmonton will not produce vitamin D3 synthesis in human skin.”
Exposures measured by Leach, 46, for office workers in Bristol England demonstrate a long period in winter with very low average exposures as shown in FIG. 1. In the winter season dietary vitamin D intake or lamp exposure can be used to obtain sufficient vitamin D. Excess dietary vitamin D intake is a potential problem. In the summer season, care can be used to avoid excess exposure. For office workers, a particular problem is the weekend and vacation exposure of untanned skin which can increase the risk of melanoma of the skin. The exposures for vitamin D generation are low for a person with typical light skin. For those with dark skin higher exposures are necessary.
Whole body exposure has the advantage of a much lower exposure per unit area of skin. This greatly reduces the risk of skin cancer. Also, the cholesterol in the skin and arterial plaque is reduced over a much larger area than the commonly exposed areas such as head and arms. Ainsley, 9, recommends periodic sunbathing for the exposure. This is practical in locations with favorable climate such as parts of California. However in most areas the primary exposure deficiency occurs in the season too cold for outdoor sunbathing. Thus lamps or ultraviolet B transmitting windows are needed. Proper levels of exposure enable reduction or elimination of excessive dietary vitamin D currently being consumed by many individuals with potential adverse health consequences.
Since one MED (Minimal Erythema Dose) whole body exposure produces approximately 10,000 IU, Goldsmith, 32, p. 939 and the adult recommended amount is 200 IU, one MED is a factor of 50 more than needed. For an adult a whole body exposure of 1/50 MED should be sufficient in the winter in latitudes where an insignificant amount of solar radiation generated vitamin D is produced and a significant amount of vitamin D is not obtained from the diet or supplements.
For the elderly, lactating women and children, the recommended amount is 400 IU so the maximum whole-body exposure needed for vitamin D generation for this group is 1/25 MED. An exposure less than the maximum is needed for those with significant vitamin D from casual solar exposure, the diet and supplements.
Dietary Vitamin D Intake
As discussed previously, the estimated per capita dietary vitamin D intake in the U.S. was 2435 IU per day, Kummerow, 45. Since Kummerow's estimate was based on the amount of vitamin D produced and only 40% of the amount produced was sold, FDA, 24, the corrected intake was about 1000 IU/day or less depending on the fraction of the amount sold that was consumed. Dale, 20, estimated the average daily intake to be 477 IU for older adolescents. The recommended daily intake for adults 25 years of age and older, other than pregnant or lactating women, is a lower value of 200 IU, Williams, 84. The average U.S. vitamin D intake is higher than the recommended intake for adults by a factor of 2.7 using Dale's estimate or a factor of 5 using the 1000 IU/day estimate.
According to Kummerow, 45, the vitamin D is added to: “ . . . baby foods, imitation dairy products, beverages, sweet sauces, prepared breakfast cereals, margarine, macaroni, noodles, farina, and flour. Most store bread has 250-750 IU/lb. added.” The toxic level of 2000-3000 IU per day, Reed, 67, is not extremely high compared to the per capita intake. For infants Sterns, 76, concluded the upper safe level to be between 800 and 1,500 IU per day since intakes in this range result in decreased growth. In addition to the other sources, vitamin D is added to animal feeds and then indirectly consumed in meat and eggs. Vitamin D occurs naturally in only a few food sources such as yeast and fish liver oils, Williams, 84. In countries such as the Netherlands where vitamin D is added only to infant formula and margarine, the age standardized circulatory disease death rate is much less than in the United States. Belgium and France also have low average dietary vitamin D intakes. In these countries the vitamin D is added to only a few food items.
TABLE 1includes an estimate of vitamin D intake using food content data fromseveral sources including Kummerow's values.Vitamin D intake estimateEstimated Intake**ConsumptionTypical content*Calculated Intake*Dale and LowenbergFood Itemlbs./yearIU/lbs.IU/dayIU/dayWheat111500152Other cereals2278446 0-35Total rice770Total sugar and sweets119Total potatoes and starchy foods100Total pulses, nuts, seeds15Total vegetables20663Total fruit156Cocoa3130011 8-38Beef1159028Veal3901Pig meat (pork and bacon)6541073Mutton, lamb and goat meat3901Poultry meat5036350Total eggs3824525Total milk products369200202325-387Cheese (hard)13161Cottage cheese5Total fish and crustaceans162700118Total oils and fats (fat content)540Margarine (fat content)1119005826-47Butter (product weight)5270036Total:806477References: Dale and Lowenberg: J. of Pediatrics, 70:952-955; 1967 OEDC (Organiz. Econ. Coop. & Develop.), Food Consumption Statistics, Paris, 1978 Kummerow: Am. J. Clin. Nutr, 32:58-83; 1979 Kummerow: Am. J. Clin. Nutr, 29:579-584; 1976 Wilson, Principles of Nutrition, Wiley, 1975. p 486 Pennington, Food Values of Portions Commonly Used, 15th Ed. 1989. Mutton, lamb and goat estimated using beef content value *For choice of food items with high vitamin D content. **Catagories not listed: Diet foods 0-20 IU/day; Natural foods 20-66 IU/day. 
A vitamin D intake from bread, meats other than lunch meat, poultry, and fish are not included in the table by Pennington, 64. If a person eats bread fortified with vitamin D the intake can be high. If a person eats a high percentage of lunch meat the vitamin D intake can be high as indicated by the values in Pennington's table. If other meats have a high content as measured by Kummerow, the vitamin D intake can be high. If vitamin D rich fish is consumed the intake can be high. If breakfast cereal fortified with vitamin D is used the intake can be high. If fortified margarine and butter are used the intake can be high. The combination of these items results in an estimated intake of over 800 IU per day as listed in table 1. This large value is not greatly less than the 1000 IU per day value derived from the amount of vitamin D that was sold in one year.
Many persons can have an intake of vitamin D higher than the average due to variations in dietary habits and the use of vitamin pills. Intake of toxic levels of vitamin D may be having serious consequences for large numbers of persons. Excess vitamin D from the diet may result in precipitation of calcium salts in the kidneys and arteries resulting in irreversible kidney damage and calcification of major arteries.
Bone Mineralization
Sunlight exposure to obtain vitamin D rather than obtaining the vitamin D from the diet has the advantage the exposure may result in added calcium to increase bone mineral density resulting in stronger bones. Also, a reserve supply of calcium in the bones is obtained for use during any periods when there may be a net loss of calcium.
Licht, 48, provides an ancient history reference to long term sunlight exposure of shaved heads resulting in increased skull mineralization in comparison with those with less long-term sunlight exposure due to headwear and hair covering. The increased skull mineralization decreases the transmitted light to the outer layers of the brain and acts in a manner similar to the tanning of the skin to protect underlying tissues. Increased bone mineralization may also serve to protect the bone marrow and blood forming processes. A rapidly changing environment such as a vacation to a sunny beach area does not allow time for protective mechanisms such as bone mineralization in addition to tanning to operate. This raises the possibility of light overexposure affecting disorders other than just the skin.
The calcium for increased mineralization is supplied by increased ultraviolet light resulting in higher dietary calcium absorption in the intestine. Kime, 42, described an experiment comparing fluorescent lamp lighting resulting in increased calcium absorption while incandescent lighting resulted in decreased calcium absorption for two groups of veterans living indoors in a soldiers home in Chelsea, Mass.
Vitamin D in Animal Rations
The control of the inside optical radiation environment for farm animals is desirable to enable the use of less vitamin D in animal rations. Reduced vitamin D in animal rations decreases the vitamin D intake of humans consuming meat. For those persons with excess vitamin D intake a reduction in vitamin D consumption may result in improved health and extended life span.
By using adjustable ultraviolet solar radiation from skylights in farm buildings it may be possible to reduce the amount of vitamin D in animal feed without reducing the food productivity. For a skylight, an additional outer reflecting section may be necessary to prevent excessive heating from the greenhouse effect for hot days. The overall reduction in the fortification of foods to reduce the per capita consumption to a value near the recommended daily allowance may have potential to significantly improve health. Obtaining more vitamin D from ultraviolet skin exposure and less from dietary intake appears to be desirable as long as great care is taken in avoiding skin overexposure as discussed by Fraser, 27.
Antioxidants
When using increased skin exposure in place of dietary vitamin D, antioxidants in the diet have increased important. According to Shigenaga and Ames, 71, the oxidant singlet oxygen is generated from oxygen by the absorption of energy from a dye activated by light. They also point out: “It has been estimated that approximately 30% of all cancers are related to the diet and that the main culprit is a dietary imbalance of too few fruits and vegetables and too much fat.”
The antioxidants Vitamins C, E and beta carotene provide resistance to some of the adverse effects of exposure. Thus, fresh fruit and vegetables containing antioxidants are important to include in the diet to reduce DNA damage. The use of as grown food in place of processed foods such as some breakfast foods and prepared frozen foods has other health advantages such as reduced trans fatty acid intake. Since DNA absorption and vitamin D formation in the skin have similar action spectra, care in skin exposure along with the diet is necessary to reduce the risk of excessive unrepaired DNA damage.
Beneficial Effects of Sunlight Other Than Vitamin D Formation
Solar radiation exposure has many other beneficial health effects besides the beneficial influences on vitamin D generation. The Maryland Heart Association found sunbathers suffer from hypertension only half as much as the general population, Kime, 42.
The exposure of the skin to an appropriate amount of blue or green light is beneficial to detoxify and stimulate the elimination of a natural metabolite, bilirubin. In the absence of light, bilirubin has to be conjugated with glucuronic acid or other sugars to be excreted effectively, McDonagh, 57. An example of the beneficial use of increased skin illumination using blue or green light is the phototherapy used for treating neonatal jaundice.
Seasonal affective disorder, SAD, is another condition treated using visible light. In dark seasons, bright artificial lights are used during reading or in the viewing direction to moderate or eliminate depression.
The nocturnal melatonin concentration depends on the circadian rhythm determined by the light variation between night and day. As discussed by Blask, 16, a high melatonin concentration may be important for low incidence for several types of cancer. Blocking the early morning sunlight in the summer by shades at windows may provide a health benefit by extending the nocturnal period of high melatonin concentration. Avoiding late night activities such as television viewing also may extend the period of high melatonin concentration.
Further, certain skin diseases, such as psoriasis and vitiligo among others may be partially alleviated by exposure to sun light or ultraviolet radiation, UV-A, with wavelengths between 315 and 400 nanometers, Bortnick, 1. Consequently a window of light transmitting material or lamp allowing the irradiation of skin may aid in the treatment and prevention of these and other diseases.
Possible Detrimental Effects of Sun or Lamp Exposure
In addition to the beneficial effects of solar radiation exposure there are many possible detrimental effects of excessive skin exposure.
Nonmelanoma skin cancer from excessive accumulated solar radiation exposure has a very high incidence. In 1977-78 the number of new cases per year was over 2 per 1000 persons, WHO, 85, page 139. Nonmelanoma skin cancer does not have a high fatality rate similar to the lower incidence melanoma of the skin, however the incidence of melanoma of the skin is increasing in many areas such as Australia.
Simone Harrison, 36, found rapid development of melanocytic nevi during childhood in Australia A large number of melanocytic nevi is a risk factor for melanoma skin cancer. Very high counts in the study in Australia were associated with estimated sun exposures of four or more hours per day. For light skinned persons in bright environments such as Australia, ultraviolet transmitting windows may not provide an advantage for much of the year. If an advantage is provided it may be for only a few brief periods.
Mangus, 54, postulated the increasing incidence of melanoma of the skin in the Nordic countries is associated with changing clothing styles and vacations. The changing clothing styles result in increased skin exposure on bright spring and summer days. Vacations to more southerly latitudes result in exposure of untanned skin to a bright solar radiation environment. A more uniform exposure to ultraviolet radiation throughout the year using UV transmitting windows may provide many health benefits without the detrimental effects associated with brief vacations to bright areas or utilization of tanning booths. Infants and children in strollers without sunshades may be subjected to overexposure especially if exposed for long periods in midday during bright summer days. Irregular exposure, being indoors much of the time, followed by a day with lots of outdoor exposure is very undesirable and a risk factor for melanoma of the skin. In the darker times of the year there is the opposite problem of obtaining sufficient exposure with the many associated beneficial effects.
Conditions other than skin cancer may have an increased risk resulting from solar radiation overexposure in bright seasons. Immune system suppression by ultraviolet radiation, Goettsch, 31, may result in increased incidences of many types of immune system related conditions. Also, ultraviolet radiation can activate the human immunodeficiency virus-1 promoter, Valerie, 78, or the virus, Stanley, 75. Effects of multiple ultraviolet exposures on transcription induction from the long terminal repeat of the human immunodeficiency virus were measured by Schreck, 68.
As discussed by Nowak, 60, the HIV virus may overcome the immume system by many mutations developing a resistant strain of the virus. The avoidance of excess mutation inducing ultraviolet exposure by those who are HIV positive may extend the latent period. Cebula, 19, describes techniques to compare lamps for selection of lamps with minimum mutagenic effects. However, ultraviolet exposure is associated with strengthening of some of the properties of the immune system. As listed by Hawk, 37, excess ultraviolet exposure can exacerbate viral infection. Until it is determined whether or not the latency period is dependent on ultraviolet exposure, it is unknown if the lamp exposure will be detrimental, beneficial or not have an effect for those who are HIV positive. Ultraviolet-B phototherapy has not demonstrated adverse short term effects for 28 HIV positive patients, Fotiades, 26. If sunlight induces the progression of AIDS, Vincek, 80, hypothesizes TNF alpha (tumor necrosis factor-alpha) and cis-UCA (urocanic acid) released by intense sun exposure can accelerate the onset and progression of AIDS in HIV-infected individuals.
Relevant Patents
The many advantages of obtaining sufficient exposure in the dark seasons and avoiding excessive exposure in the bright seasons demonstrate the need for methods and apparatus to assist in obtaining proper exposure. There are existing patents of use in conjunction with the present invention to achieve improved exposure of the skin.
The patent by Bortnik, U.S Pat. No. 4,546,493, refers to tan through garments. The types of materials used can be irritating to the skin. By using windows in conventional garment material the possibly irritating material can be offset from contact with the skin to reduce the possibility of irritation. This material can provide needed additional skin exposure in dark seasons.
The patent by Calverley, U.S. Pat. No. 5,206,229, describes vitamin D analogs for pharmaceutical use. The disclosed invention refers to methods to obtain benefits by the use of ultraviolet induced vitamin D.
The patent by Fiorenza, U.S. Pat No. 4,656,778, describes a three track storm window. By use of a ultraviolet transmitting window in one (the outer) of the three tracks and ultraviolet blocking windows in the other two tracks, a window with adjustable ultraviolet transmission can be obtained.
The patent by Ryan, U.S. Pat. No. 5,196,705, describes an exposure meter that can be used to adjust the ultraviolet transmission for an appropriate exposure either higher or lower.
The patent by Rattray, U.S. Pat. No. 4,843,279, describes a fluorescent lamp that can be used to obtain high levels of adjustable ultraviolet radiation exposure in the disclosed fixture with adjustable ultraviolet transmission.
The patent by Pepall, U.S. Pat. No. D282,581, describes a sunlamp that can be used with the disclosed adjustable ultraviolet transmission devices to obtain an appropriate ultraviolet exposure.
The patent by Dalebout, U.S. Pat. No. 5,000,444 describes a dual action exercise cycle with air resistant blade members in back. This exercise cycle is particularly well suited for the addition of irradiation lamps in back. The air blades provide air circulation for cooling of the seated individual. The air cooling helps to compensate for the additional heat from the lamps.
The patent by Young, U.S. Pat. No. D310,878 describes a tanning station for use with exercise devices. The irradiation devices of this invention typically use lower irradiances with doses less than the level for tanning. The irradiation devices of this invention are selected for vitamin D formation and potential reduction of risk of particular types of cancer, heart disease and other conditions. Tanning lamps commonly use predominantly ultraviolet A irradiation. For vitamin D generation in the skin ultraviolet B radiation is normally utilized.